A dual port syringe has an upper port for connection to a fluid reservoir
and a lower port for delivery of the medical fluid under pressure to a
patient. A first valve is connected between the fluid reservoir and the
upper port, and second valve is connected between the lower port and the
patient. During a fill operation, a piston is moved within the syringe to
drawn fluid from the reservoir into the syringe through the upper port.
During injection operation, the piston moves in an opposite direction to
force fluid out of the syringe through the lower port.